An old Star Trek joke insists that the sign on the Enterprise’s female restroom reads: “Where no man has gone before.”

Of course, intersex bathroom jokes don’t work very well anymore; but I suppose if one of those red-shirted crewmen felt really urgent and the men’s room was locked, he would have “to boldly go” — thus completing one of the most famous quotes in the history of American TV.

But that three-word verbal construct has irritated some folks, because it is a “split infinitive” — an alleged grammar error that was, for many decades, a major no-no in hifalutin English.

Last week at “Weird Words,” we tried to undo the age-old rule against using “ain’t”; so I thought that even though our bailiwick is vocab, I might knock over one or two other unnecessary linguistic taboos. (And I’ll try to go easy on the technical stuff.)

While the whole area of “infinitives” is complex, the form we’re talking about here is a simple verb preceded by to — as in the sentence “I wanted to introduce my friend.” And the so-called “split infinitive” occurs when you stick an adverb or some other phrase between the verb and the “to”: I wanted to properly introduce my friend.

According to the venerable Chicago Manual of Style — pretty much the gold standard for formal writing — the split infinitive was widely condemned as bad grammar “from about 1850 to 1925.” (No idea where they came up with such specific dates, but … I’m not gonna argue with Chicago.)

My father, a terrific writer whose journalistic career spanned nearly seven decades, once suggested that split infinitives were frowned on because they might make the adverb sound like a verb. Thus, “to not tie my shoes” could initially confuse a listener because “to not” sounds like “to knot”; so now we’re not sure if he’s actually knotting his shoes or not. Ugh. (Sorta like saying that your wedding went off “without a hitch.” Hmmm.)

But I’ve never heard Dad’s explanation anywhere else. A more likely reason is that in many languages — Italian, German, Portuguese, Russian — you can’t split an infinitive because it’s just a single word. In Spanish, for instance, “to talk” and “to sing” are simply hablar and cantar.

Along these lines, grammarian and editor Ted Johnson, with whom I worked in my copy-editing days at Simon & Schuster, says the taboo against split infinitives is “arbirtrary.” In his excellent Handbook of Good English (WSP, 1983), Johnson writes that the proscription is “a hangover from the nineteenth century, when grammarians attempted to make English grammar conform to Latin grammar. The Latin infinitive cannot be split — but only because it is all one word, not because there is any rule against it.”

That’s why several of my grammar guides don’t even mention split infinitives — including the gone-but-not forgotten Warriner’s, once the reigning champion of English grammar textbooks.

But while Johnson and Chicago both admit that avoiding split infinitives can be wise at times, it’s also clear that some sentences just sound better if you do it. I decided to quickly go to the hospital is not only better but actually clearer than I decided quickly to go to the hospital — or even, I decided to go to the hospital quickly. With the split infinitive, it’s abundantly clear which verb is being done quickly — but in the other sentences, not so much.

Incidentally, there’s a similar rule against ending sentences with a preposition — resulting in such awkward wording as “He’s the guy with whom we went” (rather than “we went with”). This likewise arbitary rule also comes from Latin, where the so-called “terminal preposition” is not possible.

We’ll deal with that annoying bugaboo next week.